influence of welding temperature and pressure on the mechanical properties of welding zone of polyethylene pipes welded via butt fusion method

In this research it was intended to find the optimum temperature and pressure of welding of HDPE80 pipes used in the gas industries after primary preparation of the samples welding procedure was performed via butt fusion method in four temperatures of 180,200,210 and 225 C and by exerting four different pressures of 1.3,1.5,1.7,1.9 kg/mm2 5.4,6.9,7.8 and 8.7 bar in each temperature 64 tensile test specimens were prepared according to ISO/FDIS 13953:2001 E standard and underwent tension test in accompany with 2 specimens of un welded pipes tension test results such as yield stress tensile strength elongation repture mode and width and heght of welding bead were studied the results showed that in constant temperature tensile strength has decreased by pressure increase except at 210 C where pressure increase from 1.3kg/mm2 5.4bar to 1.9 kg/mm2 8.7bar resulted in quantitative increase of tensile strength from 19.37 to 20 MPa.